Determining the Degree of Disability


When residual impairment continues even though maximum medical recovery (MMR) expected has been reached following an accident, the WSIB determines the degree of permanent disability. Generally, the determination is made once the condition is stable, and the worker has attained MMR, see 11-01-05, Determining Permanent Impairment.


The purpose of this policy is to set out how the degree of permanent disability is determined.


Basis for determining degree of disability

The WSIB adopted the Permanent Partial Disability Rating Schedule proposed by the Committee on Permanent Disability Evaluation of the Association of Workers' Compensation Boards of Canada in its report of September 1, 1964. Using the Association's Rating Schedule, the WSIB developed the Ontario Rating Schedule, which is periodically updated, see 18-07-02, The Ontario Rating Schedule.

Disabilities not specified in the Rating Schedule

The Ontario Rating Schedule does not address all forms of impairment. Approved clinical ratings, for some special types of permanent disability may also be found in other policy documents (e.g. see 15-04-07, Disfigurement - Permanent Disability Rating Schedule; and 15-04-06, Impotence and Sterility).

Minimum award

The WSIB recognizes a minimum permanent impairment award of 0.4%. Residual impairment below 0.4% is not regarded as representing an impairment of earning capacity.

Maximum award

The WSIB recognizes a maximum level of permanent disability resulting from any accident, as amounting to but not exceeding 100%, excluding any lump sum given for facial disfigurement (see 15-04-07, Disfigurement - Permanent Disability Rating Schedule).

Optimal time for rating

The WSIB determines the degree of permanent disability when treatment is concluded, the condition is stable, and MMR has been reached. The decision-maker determines suitability for permanent disability rating using the Referral Reference Chart (see Appendix).

Early ratings

The WSIB may approve early rating of the permanent disability when

  • the worker is taking up permanent residence outside Canada, see 15-06-07, Leaving the Province/Country
  • the worker is 100% permanently totally disabled in the opinion of the decision-maker
  • the worker has refused corrective surgery. In such a case, the WSIB initiates the assessment at the time that would normally have elapsed if surgery had been performed.

Clinical rating

The WSIB reviews the health care information available to estimate the degree of clinical impairment and determine an appropriate clinical rating. 

If the worker's physician or other health care provider cannot provide sufficient health care information to determine the degree of clinical impairment, or where the work-related impairment is complicated by other conditions, the decision-maker may arrange for the worker to attend an independent medical assessment. The WSIB sends a copy of the assessment report to the worker.

In all cases, the rating is expressed in terms of a percentage, in accordance with the provisions of the approved Permanent Disability Rating Schedule.

Indisputable ratings

An indisputable rating may be appropriate when the worker cannot attend an independent medical asessement because of

  • the death of the worker, or
  • a concurrent condition which precludes the worker from being available for an examination, i.e., hospitalization for a terminal illness.

In each case, the WSIB determines the degree of clinical impairment based on available health care information and determines a percentage figure for the disability that is consistent with the Permanent Disability Ontario Rating Schedule. The decision-maker uses this information to determine the nature and amount of the Permanent Disability Award.


If a permanent disability worsens, the WSIB may reassess the worker's disability. The degree of worsening is determined based on health care information submitted to file. The pensions awards considered include both monthly awards and previously commuted lump sum awards.

The WSIB applies the current percentage rating for the disability for which the pension was awarded, to all active, re-opened on request, or review cases.

If factors other than a change in the Ontario Rating Schedule are involved, the WSIB will give individual consideration to an appropriate adjustment.

Adjustment required by change in Ontario Rating Schedule

When warranted, an upward adjustment due to a change in the Ontario Rating Schedule may be made. The WSIB applies the date of the schedule change in determining the effective date of the adjustment.


The decision-maker informs the injured worker of the percentage of assessed disability and the approximate dollar value, and of their right to request a review of the case in the future if there is clinical documentation of a deterioration of the compensable condition. This information is also confirmed in a letter of confirmation to the worker and employer, for further information, see 18-07-03, Type and Duration of Award.

Appendix: Referral reference chart
Type of disability Referral time
Single digit 3 months after operation
Multiple digit 6 months after operation
Toes 3 months after operation
Major limbs As directed by Amputee Conference
Hip 18 months after operation
Other (knee, shoulder) 2 years after operation
Burns 2 years after accident or last major surgery
Industrial As soon as entitlement established
Traumatic 9 months after injury
Disfigurement 1 year after accident or operation
NOTE: 2 years for burns
No surgery At close of compensation benefits
Surgery 6 months after operation
Blindness At close of compensation benefits
Cataract At close of compensation benefits
Corneal scars and ulcers 1 year from end of treatment
Diplopia, hemianopia As for head injury
Enucleation At close of compensation benefits
Field defects As for head injury
Retinal detachments 1 year after surgery
Ankle 18 months after accident or surgery
Back 18 months after surgery
Colles 1 year after accident
Elbow 1 year after accident or surgery
Femur 1 year after accident or surgery
Forearm 1 year after accident or surgery
Knee joint 2 years after accident or surgery
Pelvis 18 months after accident or surgery
Os calcis 18 months after accident or surgery
Tibial shaft 1 year after accident or surgery
Upper arm 1 year after accident or surgery
Gross head injuries 2 years after accident
NOTE: major head injuries should be referred through the Neurology Clinic
Intra-abdominal 6 months after operation
Major peripheral nerve injuries 2 years after accident or surgery
Neck injuries 1 year after accident or surgery
Serious injuries to toes and forefoot 1 year after accident or surgery
Shoulder injuries 2 years after accident or surgery
Simple surgery to knee joint 1 year after accident or surgery
Spinal cord injuries 2 years

Application date

This policy applies to all decisions made on or after January 1, 2015, for accidents prior to January 2, 1990.

Document History

This policy replaces 18-07-01 dated March 3, 2008.

This document was previously published as:
18-07-01 dated October 12, 2004 
05-03-02 dated February 23, 1994.


Legislative Authority

Workers' Compensation Act, R.S.O. 1980, as amended
Sections 45(1)(3), 132


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